The present invention relates to endoluminal surgical procedures and devices and, more particularly, to an endoluminal method and apparatus that facilitates the prevention of type II endoleaks associated with post stent-graft treated arterial aneurysms.
For a significant portion of the general public, abdominal aortic aneurysms (AAA) represent a major medical problem. Aneurysms are a form of atherosclerosis characterized by degeneration of the arterial wall in which the wall weakens and balloons outward by thinning. The conventional approach to repairing aneurysms involves a very invasive operation entailing the dissection of the aorta and replacement of the aneurysm with an artificial artery known as a prosthetic graft. In order to expose the aorta and perform this procedure, a significant abdominal incision extending from the breast bone to the pubic bone is required.
Over recent years, however, physicians have made widespread use of a significantly less invasive approach to aneurysmal repair involving the transluminal placement of an endoluminal graft within the aorta. With the use of expandable stents, the graft is attached to the internal surface of the arterial wall, above and below the aneurysm, without sewing. Once in place, the blood flows through the graft by-passing the aneurysm.
It has been reported, however, that about thirty percent of all aneurysms repaired with endoluminal stent-grafts fail to adequately exclude the associated aneurysmal sac from systematic aortic pressures. Eighty percent or more of these failures are said to be due to type II endoleaks. Type II endoleaks occur when blood flow takes a circuitous route traveling through branches from the non-stented portion of the aorta through anastomotic connections into collateral vessels with a direct communication with the aneurysmal sac. Blood then travels in a retrograde direction in these collateral vessels, eventually emptying into the sac behind the stent-graft. These collateral vessels, prior to aortic exclusion via the stent-graft, carried blood from the aorta to nutrient beds of lower pressure. When the aorta from which they originate is excluded, the pressure gradient favors flow in the opposite direction. In conventional surgical repairs of aneurysms, these collateral vessels are typically ligated. This is not possible with current endoluminal graft technology.
Moreover, current endoluminal graft technology does not enable a physician to stop such endoleaks once the stent-graft has been placed and the leak has formed. Although embolization has been demonstrated to occlude flow to the aneurysmal sac from embolized vessels, this approach tends to be largely ineffective. Because the aneurysmal sac provides so many paths through which blood can flow, like the xe2x80x9cnidasxe2x80x9d of an arterial-venous-malformation (AVM) (see FIG. 5), it is difficult to stop the flow entirely without destroying the xe2x80x9cnidas.xe2x80x9d
Thus, it is desirable to provide a method and apparatus that facilitates the prevention or elimination of type II endoleaks in stent-graft treated aneurysmal sacs and other arterial aneurysms.
The present invention is directed to a method and apparatus that facilitates the prevention or elimination of type II endoleaks in stent-graft treated arterial aneurysms, such as aneurysms occurring in the abdominal aorta, the iliac, the thoracic aorta, and the like. In a preferred embodiment, an apparatus of the present invention comprises a perfusion balloon catheter having an elongate tubular body with a balloon mounted on the body adjacent its distal end. The balloon preferably comprises a plurality of energy conducting elements attached thereto for transmitting RF energy to tissue to be treated. Alternatively, the apparatus of the present invention may comprise a catheter having an elongate tubular body with a wire mesh basket extending from its distal end. An articulating wire attaches to the distal end of the wire basket and extends through the catheter body. When pulled, the articulating wire applies a force to the distal end of the basket to compress the basket longitudinally and expand the basket radially.
In operation, e.g., for treatment of an abdominal aorta aneurysm (AAA), the catheter is inserted into a femoral artery of a patient and then advanced through the femoral artery into the aorta until the balloon or basket is positioned within the aneurysmal sac. Once in place, the balloon or basket is expanded to compress a clot material within the aneurysmal sac and close collateral blood flow pathways through the clot material. The compression is preferably conducted under a pressure in the range of about 2-5 atmospheres. While compressed, the clot material is heated by transmitting RF energy to the wire basket or the conducting elements on the balloon until the clot material is cauterized or coagulated and collateral blood flow pathways through the clot material are occluded. Other means of heating may include inductive or direct current (DC) heating. The balloon or basket is then returned to an unexpanded state and the catheter is removed from the aorta. Once the catheter is removed, a stent-graft may be placed within the aorta in accordance with conventional endoluminal graft methodology.
Further, objects and advantages of the invention will become apparent from the following detailed description and accompanying drawings.